#include "crypt.h"
#include <fstream>
#include <iostream>
#include <vector>

using namespace std;

int encrypt(int offset, char *buf, int len) {
    if (offset < 0) {
        return -1;
    }
    for (int i = 0; i < len; ++i) {
        buf[i] ^= mapL(offset + i);
    }
    return 0;
}

char mapL(int v) {
    static const int key[] = {
        0x77, 0x48, 0x32, 0x73, 0xDE, 0xF2, 0xC0, 0xC8, 0x95, 0xEC, 0x30, 0xB2,
        0x51, 0xC3, 0xE1, 0xA0, 0x9E, 0xE6, 0x9D, 0xCF, 0xFA, 0x7F, 0x14, 0xD1,
        0xCE, 0xB8, 0xDC, 0xC3, 0x4A, 0x67, 0x93, 0xD6, 0x28, 0xC2, 0x91, 0x70,
        0xCA, 0x8D, 0xA2, 0xA4, 0xF0, 0x08, 0x61, 0x90, 0x7E, 0x6F, 0xA2, 0xE0,
        0xEB, 0xAE, 0x3E, 0xB6, 0x67, 0xC7, 0x92, 0xF4, 0x91, 0xB5, 0xF6, 0x6C,
        0x5E, 0x84, 0x40, 0xF7, 0xF3, 0x1B, 0x02, 0x7F, 0xD5, 0xAB, 0x41, 0x89,
        0x28, 0xF4, 0x25, 0xCC, 0x52, 0x11, 0xAD, 0x43, 0x68, 0xA6, 0x41, 0x8B,
        0x84, 0xB5, 0xFF, 0x2C, 0x92, 0x4A, 0x26, 0xD8, 0x47, 0x6A, 0x7C, 0x95,
        0x61, 0xCC, 0xE6, 0xCB, 0xBB, 0x3F, 0x47, 0x58, 0x89, 0x75, 0xC3, 0x75,
        0xA1, 0xD9, 0xAF, 0xCC, 0x08, 0x73, 0x17, 0xDC, 0xAA, 0x9A, 0xA2, 0x16,
        0x41, 0xD8, 0xA2, 0x06, 0xC6, 0x8B, 0xFC, 0x66, 0x34, 0x9F, 0xCF, 0x18,
        0x23, 0xA0, 0x0A, 0x74, 0xE7, 0x2B, 0x27, 0x70, 0x92, 0xE9, 0xAF, 0x37,
        0xE6, 0x8C, 0xA7, 0xBC, 0x62, 0x65, 0x9C, 0xC2, 0x08, 0xC9, 0x88, 0xB3,
        0xF3, 0x43, 0xAC, 0x74, 0x2C, 0x0F, 0xD4, 0xAF, 0xA1, 0xC3, 0x01, 0x64,
        0x95, 0x4E, 0x48, 0x9F, 0xF4, 0x35, 0x78, 0x95, 0x7A, 0x39, 0xD6, 0x6A,
        0xA0, 0x6D, 0x40, 0xE8, 0x4F, 0xA8, 0xEF, 0x11, 0x1D, 0xF3, 0x1B, 0x3F,
        0x3F, 0x07, 0xDD, 0x6F, 0x5B, 0x19, 0x30, 0x19, 0xFB, 0xEF, 0x0E, 0x37,
        0xF0, 0x0E, 0xCD, 0x16, 0x49, 0xFE, 0x53, 0x47, 0x13, 0x1A, 0xBD, 0xA4,
        0xF1, 0x40, 0x19, 0x60, 0x0E, 0xED, 0x68, 0x09, 0x06, 0x5F, 0x4D, 0xCF,
        0x3D, 0x1A, 0xFE, 0x20, 0x77, 0xE4, 0xD9, 0xDA, 0xF9, 0xA4, 0x2B, 0x76,
        0x1C, 0x71, 0xDB, 0x00, 0xBC, 0xFD, 0xC,  0x6C, 0xA5, 0x47, 0xF7, 0xF6,
        0x00, 0x79, 0x4A, 0x11};

    if (v >= 0) {
        if (v > 0x7FFF) v %= 0x7FFF;
    } else {
        v = 0;
    }
    return char(key[(v * v + 80923) % 256]);
}

bool convert(const std::string &in, const std::string &out) {
    static char buf[BUFFER_SIZE];

    ifstream fin(in, ios::binary);
    if (!fin.is_open()) {
        cerr << "opening file " << in << " failed.";
        return false;
    }
    ofstream fout(out, ios::binary);
    if (!fout.is_open()) {
        cerr << "opening file " << out << " failed.";
        return false;
    }

    int offset = 0;
    while (true) {
        fin.read(buf, BUFFER_SIZE);
        int length = fin.gcount();
        encrypt(offset, buf, length);
        fout.write(buf, length);
        offset += length;
        if (!fin) break;
    }

    return true;
}
